<u># 用法</u>
<em>返回一个ReadableStream对象，读取它将返回包含在Blob中的数据</em>
<u># 语法</u>
<em>const ReadableStream</em> = <em>blob</em>.<b>stream( )</b>
<u># 示例</u>
<em>const stream</em> = <em>blob</em>.<b>stream( )</b> 		<em>// => ReadableStream {locked: false}</em>